The sea of oil and natural gas underneath North Dakota is far larger than first thought.

There are 7.4 billion barrels of recoverable oil in the western part of the state and extending into Montana, according to the latest estimate by the U.S. Geological Survey.

That’s more than twice the oil the USGS estimated could be recovered five years ago. What’s more, the USGS has nearly tripled its estimate of the natural gas available in the area.

The revised totals could make the North Dakota field the greatest oil and gas find ever in the continental United States, topping the fabled East Texas field that made Texas synonymous with oil wealth. And it would put North Dakota second to Prudhoe Bay as the largest oil producer in U.S. history.

Experts within the energy sector believe the latest government estimate might have to be revised upward too.

“We think it’s even a little bit conservative,’’ said Ron Ness, president of the North Dakota Petroleum Council.

The new estimate will give fresh momentum to an economic boom within the state that has made it the fastest growing in the nation in both population and incomes. Per capita income has risen to $52,000 a year, sixth-highest in the nation, and once quiet farm towns have been overwhelmed by oil field workers, creating shortages of housing and services.

The USGS said the drilling of 4,000 wells since 2008 in what is known as the Bakken formation has given geologists a better idea of the riches underground. The new analysis also highlights the rapid ascent of North American oil and gas production driven by the advent of the technique known as hydraulic fracturing.

Most of the additional oil and gas revealed Tuesday is in what’s called the Three Forks formation, which lies about 100 feet below the better-known Bakken formation and has only recently been explored.

As technology improves, estimates of the recoverable oil in the basin are likely to grow, Ness said. For comparison, in 1995, the USGS estimated that 151 million barrels of oil could be recovered from the Bakken shale formation.

Continental Resources, the largest acreage-holder in the North Dakota oil patch, estimated in December that the basin contains 20 billion barrels of oil and 4 billion barrels of liquid natural gas.

The USGS estimate is important, Ness said, because it comes from a government agency. “The banks and the investors really look at the USGS as the standard,” he said.

The new estimates should give potential investors confidence that the oil boom could have decades to run. At the current rate of production — 22.5 million barrels in January — it would take 27 years to remove 7.4 billion barrels from the ground.

That’s important as businesses look at investing around Williston, governments weigh building roads and energy companies decide whether to invest in the infrastructure for processing natural gas, said Rob Grunewald, an economist at the Federal Reserve Bank of Minneapolis.

“I think that those who are making investments in the region can make those investments with confidence,” Grunewald said.

One investment that would please both environmentalists and energy companies would be a better system for handling the basin’s natural gas, now estimated at 6.7 trillion cubic feet of dry gas and more than 500 million barrels of the more valuable liquid gas.

Almost a third of the gas that comes out of the Bakken now is flared — burned off immediately — creating thousands of flames that light the night sky. The state penalizes companies that flare gas for too long, but moving the gas from well to pipeline is more complicated and less lucrative than moving oil, and the infrastructure to do so has not developed quickly.

But liquid natural gas prices have fared better in the past year than prices for dry gas. Companies are beginning to build facilities to separate the liquids, and pipelines to move them.

“Oil companies, environmentalists, everyone is wanting to capture those gases and put them into production,” Grunewald said.

It’s all good news to Jason LaValley, who owns one of the many Minnesota firms benefiting from North Dakota’s boom. His 20-worker company, LaValley Industries in Bemidji, makes equipment that handles pipes for drilling and for distribution lines.

“We’re beginning to do a lot of work out there, and knowing that there’s three times as much [oil], that’s three times as much business for us,” LaValley said.

The Wisconsin Assembly planned to finish its work for the year Thursday by approving $350 million to build a new prison and provide all parents a $100 per-child tax rebate, although it's uncertain whether either will pass the Senate.